Expermiting with Scope SH4
 

In sh4 no matter the angle you can hit your target from 270, 180, 90, 0, using the bow tubes. the solution for firing of fish at 270 for example optimal track is to have the target ship at 6 knots and AOB from 90-98 when shooting from the bow tubes and your boat is heading east , you will need to aligin the scope at 270 and set your paramitters .. AOB at 98 , speed at 6knts , the range at 1300 -- you will than align your scope at 260. your torpedo settings , will be contact and speed set at high . you can only allow the Sub speed at 1 knt , once the bow of the ship hits the 260 mark fire at points as the ship passes , the bow , amidships , stern .. this also can be used for the stern tubes ,, I have found out that a 10 degree lead will hit the ship at the 0 spot from were you have aimed , reading Old Is US Navy manuels and practising formulas I have found this works effectivly . Using Manuel targeting is so much more fun .. Since the scope in Sh4 different than SH5 . I had to figure out a way to measure the ships speed using the scope ... Look at fig 1 below.
http://i.imgur.com/v5pxMn3.jpg fig 1

I found out using sh4 scope that if you count the gradients from the stern of the ship to bow of the ship by 5 (scope has to be in the close up view )

you count the stern from the centerline of the scope to the lenght of the ship , multply that by how many marks .. thus if you see 7 mark's, 7 x 5 = 45, 45 x2 = 90 ft you than take the bow of the ship and start your clock and count how many seconds it takes for the centerline to reach the stern. if it took 45 secs than muliply .45x 90 = 40.5 divide that by 3 than you will get your speed 13.5 knts , take this and divide that by 2 and you will get your true speed of 6.75 knts

So far this has been working .. Any suggestions of caculating legnth and speed withSH4 besides the plotting map method would help .. Thanks , happy hunting

Looks elegant but 7x5=35 not 45 so your solution depends on you making an error in calculation. I would suggest this is not a method that works because errors are random. Why do you arbitrarily change a unit of time, 45 seconds, into a fractional parameter, .45, for your calculation? You don't establish any logic to the method. And why divide by 3? Why then divide again by 2? And why not just divide by 6? And where does the 6 come from and why is it used?

I don't see math, I see black magic. I don't see method, I see superstition. Personally I use my shoe size.:D:D:D

How about deriving your numbers and explaining why your method works? Start with how your speed has anything to do with the length of the ship you are measuring with your telemeter marks. Then I'll bring in CapnScurvy to explain how and why you can't use the telemeter marks in stock SH4.

A mod wish,, a way to adjust range, angle on bow and speed,, in the attack map screen ,, I've gotten the input into the torpedo solution close with about 4 trips back en forth to the periscope to get where I can fire.. or is that to much of a cheat

Adjusting parameters on the attack map screen is a kludge from SH3. It isn't realistic there either. The attack map simulates the check that was made between actual target position and the position in the TDC, which was made before every shot. If they were not in agreement the sub didn't shoot.

But the man responsible for that check did not set AoB, target speed, range or bearing into the TDC. He was the independent observer that kept the TDC team honest. This was true on US and German boats.

I have no idea where the SH3 kludge came from. But it's wrong. We shouldn't imitate it in SH4.

You can estimate speed if you know the range by measuring the time to traverse 10 degrees (or any other number of degrees).

However, this method requires some trigonometry so a prepared table of values is the best way to employ this method.

Good luck with that....

Is there another way to put input into the TDC other than in the periscope ,and the sonar station ????

"Up periscope!"... "Bearing - Mark! Down scope!" start the stop watch... three minutes fifteen seconds later: "Up periscope!... Bearing - Mark! Down scope!"... calculate... position boat for intercept, set torps, etc. Follow sonar trace lines... "Up periscope!... Bearing - $#!+, dad-blame... Down scope!"... smack XO. Duck... Re-do... :salute:

Actually I like Rockin's Intercept and 3min rule,, he had a nice video on how to very effective,, I do alot with the radar to set up but of late I've been using the TDC turned on and trying to take the shot that way but going back an forth to attack map is a pain.., what is one to do for realism

Nope, that's it, just like the real submarine. It was the torpedo men who manually put the numbers in or the TDC operator who ran the automatic inputs. Sonar also could enter range and bearing only.

It works well enough within its limitations.

Personally, I like the math part of SH so I tend to mess around with that a lot.

I especially enjoy a sonar only approach and firing. Handy when the visibility is zero off the Japanese coast.

The time to traverse 10 degrees, even with range known, is insufficient information by itself to hit any target except by pure coincidence. Lacking valid methodology, good luck is your only friend.

The only information required for a zero gyro angle firing solution is the target speed and the torpedo speed. You generate a firing bearing from these two numbers.

The arctangent of the (target speed divided by the torpedo speed) generates the deflection required at any range.

Time to transit X degrees is most useful when firing using sound bearing only in SH4 because there is a gap in sound bearings.

As an example, if I have determined target speed to be 10 knots and plan to fire 29 knot electric torpedoes, I know my deflection is 19 degrees. Firing bearing is 19 (Port AOB) or 341(Starboard AOB) for bow torpedoes.

I close to my planned firing range of 1000 yards.

From my prepared table, I know that the target will traverse 10 degrees at 1000 yards in 31 seconds or about 1 degree every 3 seconds.

When I get a clean sound bearing 20 degrees or less from my firing bearing I note the second hand and do the math to the firing bearing. I fire when the time expires.

If my firing bearing is 19 degrees and I get a clean sound bearing of 25 degrees, I time 18 seconds (3 seconds per degree for 6 degrees) and push the fire button)

The limitations of this, of course, are that the target course must be nearly perpendicular to your line of sight for this method to have accuracy but this fits the minute before firing well.

Dick O'Kane refers to his "seaman's eye" referencing one of Tang's misses where he did not update target speed based on what he saw in the periscope, instead relying on the solution developed by plot and the firing party. His experience determining speed by rate of bearing change is "seaman's eye".

Hard to do in the game but not impossible and, of course, shooting from in close forgives speed errors to a large degree.

If your torpedo does not hit precisely where the wire is at firing then you made a speed error somewhere when shooting zero gyro angle.

Can't really do better than this,,
 

Here is a film of my Zero Gyro Angle attack method.

https://youtu.be/gOFROfDUhRc

Notes:

If you take positions every three minutes the yards moved divided by 100 =knots of speed for the target. You will see a series of 3 minute positions showing 1000 yards each interval for a target speed of 10 knots.

All bow torpedoes are set to run at 46 knots. The old Mark 14's must be set to high to do this (Tubes 1 through 4) Tubes 5 and 6 have Mark 23's which only have the 46 knot speed setting.

Deflection angle for 10 knot target with 46 knot torpedo can be found on the Wiki chart
https://en.wikipedia.org/wiki/Torped...ctionAngle.png

Or you can use this calculator
http://www.couscouscrabcakes.com/okane.html

Or you can make your own table of values in Excel using =DEGREES(ATAN Target Speed/Torpedo Speed)

https://s10.postimg.org/7skqmalgp/torpedo_table.png

Notice there is no need to put anything into the TDC with this method.

Once I know the target speed all I do is get to my shooting position, 1000 yards or less from target track and 100 degrees Torpedo track angle (The angle formed by the target track and the torpedo track)

The calculated firing bearing in the film is 12 degrees starboard which is a bearing of 12 degrees. If the target where approaching from submarine port side (Starboard AOB) the firing bearing would be 12 degrees port or 348 degrees.

Range is unnecessary for this method as the ratio of the target speed to torpedo speed remains the same, thus the angle does not change with range to target.